Strong isotopic selectivity on dication formation of benzene

Abstract

Double ionization of benzene initiates a competition between its fragmentation driven by Coulomb repulsion and dication stabilization, in which the molecule undergoes a strong geometric rearrangement. We find experimentally that stabilization following an electron-impact-induced double-ionization is remarkably sensitive to the isotopic replacement of just one $^{13}\mathrm{C}$ atom in the benzene ring. This result has no analog in dications of smaller molecules. The large reactivity of medium-size hydrocarbon dications points towards an alternative route to imprint isotopic signatures in astrophysical processes.